Question 1

Hydrodynamic focusing in flow cytometry is important because it:&#10;A) Directs the laser light&#10;B) Intensifies the laser light with mirrors&#10;C) Collects the scattered light&#10;D) Creates a core of individually aligned cells

Accepted Answer

Hydrodynamic focusing in flow cytometry creates a sheath fluid that surrounds and aligns cells into a single file stream, creating a core of individually aligned cells that pass through the laser beam one at a time. This ensures accurate and consistent readings of each individual cell.

Question 2

Forward scatter is related to what cellular feature?&#10;A) Density&#10;B) Size&#10;C) Granularity&#10;D) Complexity

Accepted Answer

Forward scatter is related to the size of the cell. It measures the intensity of the light that is scattered forward as the cell passes through a laser beam. Larger cells will scatter more light than smaller cells.

Question 3

A patient has a white cell count of 12.6 *10⁹/L, hematocrit of 28%, and platelet count of 27*10⁹/L. Examination of a Wright-stained blood film reveals that almost all of the white cells in peripheral blood are blasts; the bone marrow is hypercellular with very little fat and is packed with blasts. Flow cytometry is performed on the peripheral blood cells, and a large cluster of cells is present that mark with CD20 and have monoclonal $\kappa$ light chains present on their surface. This patient has a:

A) Myeloid leukemia
B) Mature B-cell malignancy
C) Reactive B-cell hyperplasia
D) Mature T-cell malignancy

Mature B-cell malignancy

Accepted Answer

The presence of blasts in the peripheral blood and bone marrow, along with low hematocrit and platelet counts, suggests a hematologic malignancy. The fact that the white cells in peripheral blood are predominantly blasts also suggests a lymphoid malignancy, rather than a myeloid leukemia. The flow cytometry results showing a large cluster of cells marking with CD20 and monoclonal light chains identifies a B-cell malignancy, rather than a T-cell malignancy or reactive hyperplasia.

Question 4

All of the following are true concerning hematopoietic stem cells except:&#10;A) They express both CD34 and CD117 (c-kit).&#10;B) They lose some antigens as they mature.&#10;C) They express both CD4 and CD34.&#10;D) They gain lineage-specific antigens as they mature.

Accepted Answer

Hematopoietic stem cells do not express CD4, only CD34 and CD117 (c-kit).

Question 5

Staining a sample with deoxyribonucleic acid (DNA) dyes such as propidium iodide is done to determine cell:&#10;A) Viability&#10;B) Ploidy&#10;C) Lineage&#10;D) Chromosome number

Accepted Answer

The answer of Staining a sample with deoxyribonucleic acid (DNA)...

Question 6

Myeloid stem cells and blasts express which of the following on their surface?&#10;A) CD4&#10;B) CD8&#10;C) CD34&#10;D) Terminal deoxynucleotidyl transferase (TdT)

Accepted Answer

CD34 is a marker commonly found on the surface of myeloid stem cells and blasts, indicating their undifferentiated state.

Question 7

Which of the following is evaluated using fluorochrome dyes that are bound to monoclonal antibodies?&#10;A) Membrane antigens&#10;B) Nuclear complexity&#10;C) Number of lymphocytes&#10;D) Cell size

Accepted Answer

Fluorochrome dyes are commonly used in flow cytometry to label and detect specific membrane antigens on cells. Monoclonal antibodies are designed to target and bind to specific antigens, and are then labeled with a fluorochrome dye for detection by the flow cytometer. Nuclear complexity, number of lymphocytes, and cell size are typically evaluated using other methods in flow cytometry.

Question 8

What marker is most closely related to disease progression in acquired immune deficiency syndrome (AIDS) patients?&#10;A) CD3&#10;B) CD4&#10;C) CD8&#10;D) CD10

Accepted Answer

The CD4 marker is most closely related to disease progression in AIDS patients. CD4 cells are helper T cells that are destroyed by the HIV virus, resulting in a weakened immune system and progression to AIDS. As CD4 numbers decline, the risk of developing opportunistic infections and cancers increases, and this marker is used to monitor and manage the disease. CD3 and CD8 are also important markers in AIDS, but they are not as closely related to disease progression as CD4. CD10 is not a marker typically associated with immune function or AIDS.

Question 9

What cell type expresses CD20 and contains immunoglobulin light chains on the surface but not in the cytoplasm? A) Helper T cells (T_H) B) T suppressor cells C) Immature B cells D) Mature B cells

Accepted Answer

CD20 is a marker for B cells, and mature B cells express CD20 on their surface. Additionally, mature B cells express immunoglobulin light chains on their surface as part of their B cell receptor complex, but these chains are not found in the cytoplasm. Therefore, the best choice is D: Mature B cells.

Question 10

The presence of TdT is characteristic of progenitors of which lineage?&#10;A) Megakaryocytes and platelets&#10;B) Monocytes&#10;C) Erythrocytes&#10;D) Lymphocytes

Accepted Answer

TdT (Terminal deoxynucleotidyl transferase) is an enzyme that adds random nucleotides to the 3' end of DNA during V(D)J recombination, a process that occurs in developing lymphocytes. Therefore, the presence of TdT is characteristic of lymphoid progenitors.

Question 11

Which of the following is true regarding the relationship between flow cytometry and the microscopic evaluation of leukemic cells?&#10;A) Flow cytometry has made microscopic analysis outmoded.&#10;B) Methods are best used together to establish a diagnosis.&#10;C) More cells can be analyzed by looking under the microscope.&#10;D) The human eye is more sensitive than flow cytometry and better at finding weak antigenic expression.

Accepted Answer

The answer of Which of the following is true regarding...

Question 12

What is an early marker of erythroid precursors?&#10;A) CD45&#10;B) CD71&#10;C) CD34&#10;D) CD8

Accepted Answer

The answer of What is an early marker of erythroid...

Deck 33: Flow Cytometric Analysis in Hematologic Disorders